Thursday, February 14, 2008

Indicators of Deteriorating Weather:Clouds lowering and thickening, ceiling lowers. Puffy clouds begin to develop vertically and darken. Sky is dark and threatening to the West. Clouds increasing in numbers, moving rapidly across the sky. Clouds at different heights moving in different directions. Clouds moving from East or Northeast towards the South. Heavy rain occurring at night. Barometer falling steadily or rapidly. Smoke from stacks lowers. Static on AM radio. Wind shifting North to East and possibly through East to South. There is a ring (halo) around the moon. If on land, leaves that grow according to prevailing winds turn over and show their backs. Strong wind and / or a red sky in the morning. Temperatures far above or below normal for the time of year.

Indicators of Impending Precipitation:Distant objects seem to stand above the horizon. Sounds are very clear and can be heard for great distances. Transparent veil-like cirrus clouds thicken, ceiling lowers. Hazy and sticky air. Rain may occur in 18-36 hours. Halo around the sun or moon. Increasing South wind with clouds moving from the West. Wind (especially North wind) shifting to West and then South. Steadily falling barometer. Pale sunset. Red sky to the West at dawn. No dew after a hot day.

Indicators of Continuing Fair Weather:Early morning fog that clears. Gentle wind from the West or Northwest. Barometer steady or rising slightly. Red sky to East with clear sky to the West at sunset. Bright moon and light breeze at night. Heavy dew or frost. Clear blue morning sky to West. Clouds dot the afternoon summer sky.

Acid Rain: Rain that is more acidic than normal precipitation because water vapour has condensed on to particles of sulphate or nitrogen oxide. Adiabatic: Changes in temperature caused by the expansion (cooling) or compression (warming) of a body of air as it rises or descends in the atmosphere, with no exchange of heat with the surrounding air. Advection: The transfer of heat by the horizontal movement of air or water, such as a warm wind or ocean current. Advection Fog: Fog caused by the condensation of water vapour when warm, moist air crosses cold ground or sea. Air: A naturally occurring mixture of gases, chiefly nitrogen and oxygen with small amounts of argon, carbon dioxide, and water vapour. Air also usually contains dust and pollen. Air Mass: A large body of air with the fairly uniform temperature and humidity of its source region. Air Pressure: The weight of the atmosphere pressing down on the Earth's surface. The effect is caused by gravity. Also called 'atmospheric pressure'. Albedo: The measure of the reflectivity of a surface. Anabatic: Rising, as when air moves up a hillside. Anemometer: An instrument for measuring the force and speed of wind. Angular Momentum: The energy of motion of a spinning body or mass of air or water. Its value depends on the mass of the body, its radius of spin, and its rate of spin. Angular Velocity: The rate at which a spinning body, such as a planet, rotates. The Earth rotates at 15 degrees per hour, which is its angular velocity. Anticyclone: A large area of high atmospheric pressure, characterised by outward-spiralling winds - a "high". Atmosphere: A layer of gases surrounding a planet - on the Earth, chiefly made up of the gases Oxygen, Hydrogen and Nitrogen. Atmospheric Pressure: The weight of the atmosphere pressing down on the Earth's surface. The effect is caused by gravity. Also called 'air pressure'. Atoms: The smallest parts of an element - such as hydrogen or oxygen.

This valentine's day in Chennai was hot & humid.In the morning like in mid November, it was threatening to rain.Heavy cloud formation was there... but no rain.Last 3 days, the humidity is going down and even the minimum temperature is also going down.We might face a small period of DRY CHILL before we march into the HOT hotter days.The February so far is unusually hot & humid, and with 2 good mini showers.